MY 2019 and MY 2020 I believe had changes to the spec of the 300 Lux versions:
So My 2019 got Full Leather heated seats, for MY2020 this changed to the bucket seats (also heated).
There may of been other things.
As for difference between the Cupras, what do you mean exactly? There have been a number of different versions of the years. of the Mk3, below is something I did for someone else who was asking about the different ones brakes wise.
Prefacelift Cars Mk3 Manual handbrake - All FWD
265/
280/
290 3 door hatch manual
280/
290 3 door hatch manual 370mm
Sub8/Performance Pack
280/
290 3 door hatch DSG
280/
290 3 door hatch DSG 370mm
Sub8/Performance Pack
280/
290 5 door hatch manual
280/
290 5 door hatch manual 370mm
Sub8/Performance Pack
280/
290 5 door hatch DSG
280/
290 5 door hatch DSG 370mm
Sub8/Performance Pack
280/
290 ST manual
280/
290 ST manual 370mm
Sub8/Performance Pack
280/
290 ST DSG
280/
290 ST DSG 370mm
Sub8/Performance Pack
Prefacelift Cars Mk3.5 Electronic handbrake:
UK:
300 3 door hatch manual
300 3 door hatch DSG
300/290GPF 5 door hatch manual
300/290GPF 5 door hatch manual 370mm Performance Pack/R Hatch
300/290GPF 5 door hatch DSG
300/290GPF ST manual
300/300GPF ST DSG 4Drive
300/300GPF ST DSG 4Drive 370mm Performance Pack/Carbon/R ST
Europe:
300 3 door hatch manual 370mm Performance Pack (Europe only)
300 3 door hatch DSG 370mm Performance Pack (Europe only)
300/290GPF 5 door hatch DSG 370mm Performance Pack (Europe only)
300/290GPF ST manual 370mm Performance Pack (Europe only)
300/300GPF ST DSG (Europe only)
300/300GPF ST DSG 370mm Performance Pack (Europe only)
